How to Store Lyophilized Peptides: Temperature, Moisture and Light
Lyophilized (freeze-dried) peptides are far more stable as a dry powder than in solution. Most degradation in the lab comes from three things: heat, moisture and oxygen. The guidelines below come from published handling guides by peptide manufacturers and chemical suppliers. Always follow any product-specific instructions first.
Lyophilized powder
Temperature. For long-term storage, keep sealed vials frozen. Bachem recommends a tightly closed container below −15 °C, with colder storage preferred (Bachem). Sigma-Aldrich recommends −20 °C for short-term storage and −80 °C for longer periods (Sigma-Aldrich). Lyophilized peptides are commonly shipped at room temperature, and Bachem notes that a 4 °C refrigerator is acceptable for short-term storage.
Moisture. Peptides are hygroscopic, so they pull water out of the air. Let a cold vial warm to room temperature before opening it, ideally in a desiccator, so condensation doesn't form on the powder. Then take what you need quickly and reseal the vial tightly (Bachem). Sigma-Aldrich notes that moisture exposure greatly decreases long-term stability.
Light. Store vials away from bright light (Sigma-Aldrich).
Freeze-thaw cycles. Avoid repeated freezing and thawing of both dry peptides and solutions (Sigma-Aldrich).
Peptides in solution
Peptides are much less stable once dissolved. Bachem advises against long-term storage in solution and notes that frozen solutions may be kept for a few weeks. Sigma-Aldrich gives roughly one week at 4 °C as a general guide. For anything longer, divide the solution into single-use aliquots and freeze them at −20 °C or colder, so the main stock isn't thawed repeatedly. Sigma-Aldrich recommends sterile buffers at pH 5-6 and avoiding pH above 8.
Sequences that need extra care
Some amino acids make a peptide less stable:
- Cysteine (C), methionine (M) and tryptophan (W) are prone to oxidation by air. Minimize oxygen exposure, and consider purging vials with nitrogen or argon (Sigma-Aldrich).
- Asparagine (N) and glutamine (Q), along with C, M and W, shorten shelf life and make peptides less stable in solution (Bachem).
Quick reference
| Condition | Guideline |
|---|---|
| Long-term, dry | Frozen, sealed: below −15 °C (Bachem); −80 °C for long periods (Sigma-Aldrich) |
| Short-term, dry | −20 °C (Sigma-Aldrich); 4 °C acceptable short-term (Bachem) |
| Before opening | Warm to room temperature, ideally in a desiccator |
| In solution | About 1 week at 4 °C; aliquot and freeze for longer; avoid long-term solution storage |
| Always | Avoid repeated freeze-thaw cycles, moisture and bright light |
Every Zerilyx vial carries a lot number you can match to its certificate of analysis. For how to read one, see How to Read a Peptide COA.
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